Session: 02-06: HVAC System Analysis II

Paper Number: 142401

142401 - Methodology for Calculating Avoided Ghg Emissions From Hvac Products 

Abstract: 

The built environment contributes significantly to climate change as buildings are responsible for more than 40% of global CO2 emissions. Heating, Ventilation, and Air Conditioning (HVAC) systems in buildings account for 40% of a building's carbon footprint. This makes reducing the carbon footprint of HVAC systems a critical element for solving the decarbonization puzzle. To achieve this goal, the industry needs to quantify how lifetime CO2e emissions of products sold to consumers are reduced over time.

A customized methodology has been developed to calculate the avoided emissions of HVAC products, including both residential and commercial systems. Average annual energy use is a key component of the calculation, since the lifetime CO2e indirect emissions result from multiplying the average annual energy use, CO2e emissions per unit of energy, and the product's lifetime in years. An algorithm calculates the average annual energy use for each sold HVAC product, considering factors such as rated capacity, efficiency rating metric, and average annual values of operating hours, part load ratio, and part load efficiency. Rated capacity and efficiency rating metrics are specific to the sold product. Average annual values of operating hours, part load ratio, and part load efficiency are derived from weather, building, and equipment performance and vary for each product category or sub-category.

For a given product type, the typical building application types are identified. This is followed by compiling equipment modeling data for energy performance simulation. The baseline energy model is developed using specifications from the DOE Prototype building model library for the identified building application type(s) and supplementing them with additional data as needed. Once the model is created, energy performance is calculated using Carrier’s hour-by-hour energy modeling software for all 19 ASHRAE climate zones. The model's results are post-processed to derive the energy equation factors for each climate zone and the average values of the energy factors for the relevant climate zones are computed. Validation of the methodology has been conducted against DOE standard models of the building. Over 83% of the validation results displayed less than a 1% difference from the results of the original analysis factors. Of the remaining 17% of the validation results, 75% exhibited less than a 2% discrepancy, while 25% presented less than a 5% difference from the original findings. Overall, the validation process confirmed the reliability and accuracy of the methodology.

Future work will involve formalizing the methodology into a carbon footprint calculator for HVAC products. Additionally, we plan to test the methodology using additional Carrier product categories not yet considered, as well as in other sectors such as transportation.

Presenting Author: Valerie Lisi Carrier

Presenting Author Biography: Valerie Lisi is an Associate Director of Engineering Sustainability at Carrier.

Authors:

Valerie Lisi Carrier
Ravi Annapragada CARRIER CORPORATION
Richard Lord Carrier
James Pegues Carrier
Korinti Recalde Carrier
Natasa Mrazovic Ernst & Young